From the front it will look no different. Some modification of the back of the case will be necessary and I need to explore the best internal mounting solution. Right now it fits into the current internal mechanism holder after removing all mechanical parts. A bit awkward my first try. I will work on this aspect. Hopefully, I can show photos of the internal circuit soon. All my questions are not yet answered but I am pretty excited about being able to offer this option soon.

For free skiing, it affects how fast I am moving relative to the water. A boat traveling at 34 mph on the gps in a 2 mph current feels faster or slower to the skier depending on if the boat is traveling with or against the current. Having a traditional speedo (assuming I calibrated it in open water) to compare to the GPS gives me an idea of how much I would want to adjust the speed control to counteract the current.

This is a nonissue in a slalom course since speed over ground, which GPS measures, is all we care about. But in a slalom course, I'm relying on speed control and not paying much attention to my airguide.

Not bagging on your idea. I actually think it's really great. I'm just pointing out one of the advantages, for some, of having a traditional speedo in addition to a GPS speedo.

I didn't think you were "bagging". I just never really understood the importance of speed over water vs. speed over ground. I do understand the effect of current but not in relationship to skiing. As with all things it won't be for everybody... darn it!
Thanks,
Dean